A power window system in a vehicle is installed to electrically open and close the seat windows in response to operation of switches provided at each respective vehicle seat. In such a power window system, a vehicle passenger operates his or her seat switch so that the motor drives a slide member of a regulator up or down to open or close the corresponding seat window.
The conventional technology related to the power window system is found, for example, in JP-A-10-331522, JP-A-2000-295879, and JP-A-2002-2293.
The technology described in JP-A-10-331522 relates to a power window control system having an automatic-reverse feature. The power window control system reads a door open/close signal and controls the automatic-reverse feature so as not to activate for a predetermined length of time after the vehicle door(s) are opened or closed.
The technology described in JP-A-2000-295879 relates to a method for driving and controlling an open/close object such as a power window of a vehicle. In the method, a determination is made whether there is anything blocking the open/close object from opening or closing through drive control thereover. A motor rotation signal is also counted, and the result is extracted as data indicating the actual position of the open/close object. When the power is OFF, data indicating the standstill position of the open/close object is written into storage memory. In this manner, the control process is to be simplified to detect the open/close position of the open/close object, and the memory is to have longer life for storing the standstill position of the open/close object.
The technology described in JP-A-2002-2293 relates to a system for exercising control over an open/close object exemplified by a vehicle sunroof. The control system is so configured as to properly store and maintain data about the absolute position for resetting a control circuit when a vehicle engine is started. With such a control system, the motor is controlled and forced to stop when a vehicle drive source is activated during motor operation, and then a process is executed for absolute position learning. In this manner, when the vehicle drive source is activated, if the control circuit stops its operation due to the voltage reduction, the motor never fails to stop immediately therebefore. The absolute position data of thus operation-stopped motor is then updated for storage.
In typical power window systems, there is a possibility of trapping passengers’ fingers, heads, or others between seat windows and sashes when an up-auto signal is generated through operation of operation switches provided to the respective vehicle seats. The up-auto signal is for automatically closing the corresponding seat window. As a measure to stop such “trapping”, the above power window system described in the JP-A-10-331522 or others have the mechanism of making a load detection if trapping occurs between a seat window and sash at the time of up-auto. Through such a detection, the motor is driven in reverse.
The issue here is that the vehicle seat window may not be closed shut if such an automatic-reverse mechanism operates when the window is at its close-up position. The automatic-reverse mechanism is thus so configured as not to work in the vicinity of the close-up position. With such a control system of a power window system, the close-up position of the seat windows has to be known in advance.
There is another type of power window system where an operation switch provided to the driver seat can automatically open and close all seat windows. In such a power window system, however, open/close command signals have to come and go between a master controller at the driver seat and a plurality of sub controllers at the remaining seats, thereby requiring many signal lines for the purpose. The signals coming and going between the master controller and the sub controllers also include ignition switch signals, operation-state-related signals specifically for various operation switches at the driver seat, a keyless entry system, or others. Therefore, the number of signal lines will be quite large for information exchange between the master controller and the sub controllers. In order to decrease the number of signal lines between the master controller and the sub controllers, signal transmission and reception therebetween is performed in serial communications. For serial communications, Local Interconnect Network (LIN) or Controller Area Network (CAN) is used.
The communications between the master controller and the sub controllers is quite high in reliability specifically with their signal transmission/reception and information exchange, but it is not without communications errors or failures. Considered here is a case where some communications error occurs during communications between the master controller and the sub controllers. In such a case, even if the operation switch provided to the driver seat is operated to close the open window at the front passenger seat, an up-auto signal may not be correctly issued from the master controller so that the window is not closed.
Similarly, even if the operation switch provided to the front passenger seat is operated to close its seat window using an up-auto signal coming from the corresponding sub controller, permission may not come from the master controller so that the seat window may not be closed.
With this being the case, the vehicle users will find it inconvenient.
For improvement, a method was developed, providing an AND signal based on: an ON signal of an ignition switch and another ON signal of a main switch. Such signal provision is made via backup lines, each of which establishes a connection between the master controller and one of the sub controllers. This method aims to enable the sub controllers to operate normally even if signals coming from the master controller are impaired. However, the method additionally requires a harness for the backup lines, and a component to be ready for inputs and outputs to/from the respective controllers, thereby increasing the cost. Thus, there is a demand for a system causing no inconvenience to users even if a master controller or others do not operate correctly, without an increase in cost.